1. Experimental and numerical studies of 3-D transitions & 2. Characteristics of some highly curvilinear flows

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Research proposal: 1. Channel transition flows 2. Highly curvilinear flows 1. The network of open channels supplying water to various end users from a reservoir can have a closed conduit or a rectangular concrete open channel attached to the reservoir to feed a larger trapezoidal earth channel. For efficient operation, the flow passes through a short transition. Reducing energy loss and secondary flow intensity are the main goals. Channel transitions should be shaped to limit energy losses by careful design that prevents flow separation. For instance, a warped transition linking a rectangular channel with a trapezoidal channel is a case in point. Reduced energy losses attain larger irrigation command areas. Reduced secondary flow intensity in downstream channels reduces channel erosion. The study investigates the characteristics of different transitions including the warped, wedged and cylindrical transitions. Transitions will be studied, after installing auxiliary devices (vanes & humps) to augment energy conservation and reduce secondary flow intensity. LDV (Laser Doppler velocimetry) and PIV (Particle Image Velocimetry) data will yield the mean and fluctuating velocity components to assess the energy conservation efficiency in transitions and reduction of secondary flow intensity in the downstream channels. Reynolds stress transport (RST) based CFD models will be developed to get the turbulent stresses. 2. In highly curvilinear flows, boundary layer approximations that permit one to assume that the stream wise velocity is dominant and that the transverse pressure gradient is negligible are not valid. Such flows occur in hydrocyclones, siphons and counter wall jets. To get a description of these flows, one seeks solutions that yield the details of turbulence behavior in terms of various scales, stresses and eddy characteristics. Both experimental studies and numerical modeling methods will be used. Siphons permit efficient ways of conserving stored water for end users. Improved hydrocyclones can segregate ingredients better. Efficient counter jets promote enhanced dilution of pollutants.